...to the 74 X 1/9 is really apparent from a design point of view. The transition is obvious. Major design improvements jumped off from the board onto the "19". Hard parts ? You are correct. Minimal commonality I am finding.
Probably preaching to the choir though, right ?
The REALLY biggey delta is the steering system. Ancient sector gear and pitman arm transitioning to rack-n-pinion.
- of course then there's the forward mounted cooling, and the, and the, and the, and the....Ha ha ha ha ha
The following items from my X19 stash are are a straight plug in and are going on my 850:
1-1300 wiper motor
7-Red and yellow side marker lenses
Note: 850 lug nuts are coarse thread(1.5) like VW so I am using a VW part too